Need more memory - why?

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Steve

I have an Epson ActionLaser with 2MB memory, purchased about 6-7 years
ago. I've printed somewhere around 50,000 pages of all types, and
have never run into a situation where the amount of memory appeared to
be a problem. What does additional memory do for a printer?
 
2MB is generally enough.

Here's what happens (in general):

The printer takes data in several formats, typically intermixed: text,
fonts, vector graphics, and bitmapped graphics. This all has to get stored
in memory before the print mechanism starts to work.

The printer then translates all of that into a bitmapped image of the page,
at the desired print resolution. Some printers have the option of rendering
on the fly, or rendering the entire page into memory before the print
mechanism starts. The reason for the options is that once the print
mechanism starts to move, it goes at a constant speed: if the rendering
engine cannot keep up, the print fails. This depends upon how complicated
the page is (vector graphics are a killer here). If that happens, then you
have to render the entire page first. That guarantees a successful print,
but it takes more memory. If your memory is already full of bitmapped
graphics and fonts, then you might run out of memory.

So if you get memory overflow, you need more memory (or might get by with
on-the-fly rendering); if you get a print mechanism underrun, then you need
to render to memory first (HP calls this "page protect").
 
Thanks Jerry, appreciate the thorough explanation. Can you give an
example of the type of page that's likely to choke on 2MB of memory?
Is there maybe a web page somewhere that might provide an example?

....Steve
 
Your explanation applies to the (for the most part) more expensive
printers that do their rendering "on board". Most cheaper Windows
printers, are cheaper precisely because their Windows drivers do the
rendering and then download the resultant bitmap (possibly in a
compressed or otherwise processed format) to the printer. The clue is
usually that the printer is "Windows Only". Such printers, and I
suspect that the OP's is an early example, need little more internal
memory than is required to hold a full bitmap at their maximum
resolution, but they tend to be fairly slow, because even simple text
pages have to be downloaded to the printer as a bitmap and complex
pages take a fair bit of CPU time to process. Printers that render "on
board" are usually faster but they need much more memory, both to hold
fonts and instructions and to actually do the processing - 8-12 MB
would be typical for a complex A4 page even for 300 X 300 resolution -
and more powerful and expensive ones may have much more than this (or
even their own hard disks!).
 
I'm not aware of any laser printers that do their rendering on the host.
Because of the way the mechanism works, any interruption in host processing
would keep the page from printing: laser printers (the ones I've seen) can't
stop and restart painting on the drum.
 
Others have already done so, but the general principle is that if the page
renders out to a bitmap which fits in memory you'll be okay. With on-the-fly
rendering, it's hard to predict unless you know you're stuffing it with huge
bitmapped graphics.
 
Jerry Schwartz said:
Others have already done so, but the general principle is that if the page
renders out to a bitmap which fits in memory you'll be okay. With on-the-fly
rendering, it's hard to predict unless you know you're stuffing it with huge
bitmapped graphics.
Click to expand...

Must not be too much of a problem, I guess, since it hasn't been an
issue in 50,000+ pages...
 
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